Field of the Invention
The present invention relates to an adduct of a isocyanatoalkyltrimethoxysilane with a flame retardant reactive therewith, to methods of preparing said adduct, to compositions comprising said adduct and to the use thereof.
Discussion of the Background
Binders with trialkoxysilane functionality have a great many applications, for example in scratch-resistant coating compounds (WO 2013/189882 A2), hot-melt adhesives (U.S. Pat. No. 8,535,798 B2) and sealing compounds (DE 10 2012 203273 A1) since such binders have a high degree of crosslinking on account of the trialkoxysilane structural elements they comprise.
For many applications, particularly in the public sector, sufficient flame retardancy is desirable not only for the substrates employed in the respective application but also for their surface coatings, adhesive compounds and sealing compounds. Such formulations often have unreactive flame retardants added to them along with individual formulation constituents in order to retard or even completely inhibit combustion. Examples of flame retardants employed include mineral substances, for example aluminum hydroxide or antimony oxide, and (in particular halogen- or phosphorus-containing) organic flame retardants. However, the disadvantage of additive flame retardants is that they can migrate out of the applied surface coatings/adhesive compounds thus resulting in undesired emission and reduction of the flame retardant activity.
Another disadvantage is the fact that typical trialkoxysiloxane-based binders have no flame retardant activity.
Marosi et al. (Polymer Degradation and Stability 106 (2014) 63-73) describe a phosphorus-containing triethoxysilane employed for preparing flame retardant biocomposites. However, the disadvantage here is that the flax fibers wetted with the described triethoxysilane need to be heated to high temperatures for long periods to achieve curing. Marosi et al, even cites temperatures of 130° C. and reaction times of 8 h. Such flame retardant adducts are thus not suitable for processing at low temperatures. Another disadvantage is that coatings cured at low temperatures, in particular clearcoats, which comprise such phosphorus-containing triethoxysilane compounds are very tacky.